Conventional chain drive systems for internal combustion engines generally work with rigid guide rails. The stresses occurring in such a system are often adjusted by a chain tensioner that is arranged as a rule in the slack strand of the chain. However, the behavior of the chain drive can be influenced only to a limited extent with such a means. In many cases it is determined that the chain tensioner has only a restricted influence on the force in the tight strand that is decisive for the loading of the chain.
A chain drive of the pre-cited type known from the document DE 908 694 already comprises, besides a chain tensioner in the slack strand, an additional tensioning device in the tight strand of the chain. However, the chain runs only on two chain wheels, one of which is the driving wheel and the other, the driven wheel. To render the knocking of the chain as silent as possible and to prevent the occurrence of frictional forces, it is proposed to vulcanize profiled rubber or the like on the tension strip of the chain tensioner. This document does not suggest any further measures particularly such for reducing the force in the tight strand that is determinative for the loading of the chain.
As a rule, the excitations occurring during the operation of internal combustion engines such as the torsional vibrations of the crankshaft and the natural vibrations of driven shafts, lead to a strongly pulsating course of the chain force. This fluctuates constantly between a minimum and a maximum value. In most cases, the minimum value is zero while the maximum value is often a very high value that occurs for a very short period of time, that is to say, it is a peak value. This high value of the force determines the loading of the chain drive components